Identification of Self-Incompatibility Alleles by Specific PCR Analysis and <i>S-RNase</i> Sequencing in Apricot

• Main Authors: Sara Herrera, Javier Rodrigo, José I. Hormaza, Jorge Lora
• Format: Article
• Language: English
• Published: MDPI AG 2018-11-01
• Series: International Journal of Molecular Sciences
• Subjects: apricot; Gametophytic Self-Incompatibility; pollen TUBE; pollination; <i>Prunus armeniaca</i>; <i>S</i>-alleles; <i>S</i>-genotype
• Online Access: https://www.mdpi.com/1422-0067/19/11/3612

Self-incompatibility (SI) is one of the most efficient mechanisms to promote out-crossing in plants. However, SI could be a problem for fruit production. An example is apricot (<i>Prunus armeniaca</i>), in which, as in other species of the Rosaceae, SI is determined by an S-RNase-based-Gametophytic Self-Incompatibility (GSI) system. Incompatibility relationships between cultivars can be established by an <i>S</i>-allele genotyping PCR strategy. Until recently, most of the traditional European apricot cultivars were self-compatible but several breeding programs have introduced an increasing number of new cultivars whose pollination requirements are unknown. To fill this gap, we have identified the <i>S</i>-allele of 44 apricot genotypes, of which 43 are reported here for the first time. The identification of <i>S_c</i> in 15 genotypes suggests that those cultivars are self-compatible. In five genotypes, self-(in)compatibility was established by the observation of pollen tube growth in self-pollinated flowers, since PCR analysis could not allowed distinguishing between the <i>S_c</i> and <i>S</i>₈ alleles. Self-incompatible genotypes were assigned to their corresponding self-incompatibility groups. The knowledge of incompatibility relationships between apricot cultivars can be a highly valuable tool for the development of future breeding programs by selecting the appropriate parents and for efficient orchard design by planting self-compatible and inter-compatible cultivars.